The use of titanium or titanium alloy covering cardiac pacemakers is well known. In some instances such pacemakers are hermetically sealed in the titanium or titanium alloy housing while in others the pacemaker is encapsulated in a polymer and the titanium housing is provided primarily for shielding to reduce the effect of interference on the action of the pacemaker. In some instances the titanium or titanium alloy housing forms a part of the stimulating circuit of the pacemaker and requires intimate contact with the body of the patient. In other instances no such contact is required between the titanium housing and the body of the patient, the entire contact with the body tissue being by means of electrodes external of the pacemaker.
Whenever a titanium or a titanium alloy is exposed to the body fluids there is a possibility that a galvanic cell and galvanic corrosion may occur in conjunction with any other implanted metals in the body. Moreover, the release of titanium into the tissues surrounding the implant may at times occur.
In those instances where the titanium housing forms a part of the stimulating circuit there may be problems of skeletal muscle stimulation whenever the pacemaker is placed close to contractal tissue.